This invention is directed to oil-in-water emulsions containing silicone surfactants which have a combined HLB value of about 4-7. This is unusual because it is known that emulsions containing surfactants having combined HLB values of 4-7 are water-in-oil emulsions, and not oil-in-water emulsions.
The HLB system is based on the concept that a surfactant molecule has an attraction for both water and oil, and that the relative magnitude or the hydrophile-lipophile balance (HLB), of these attractions measures its suitability as an emulsifier for a given oil. The HLB system is based upon a numerical rating scale of from 0 to 20.
There are two basic types of emulsions, that is, water-in-oil emulsions and oil-in-water emulsions. There is a required HLB value for each type of emulsion. Water-in-oil emulsions require an HLB value of 4-7. Oil-in-water emulsions require an HLB value of 8-18. Generally, no emulsions result with an HLB value below 4 or an HLB value above 18.
Since oil-in-water emulsions require an HLB value of 9-16, it is therefore highly unusual and unexpected that one could prepare an oil-in-water emulsion with HLB value required for water-in-oil emulsions. This is the crux of the present invention.